Summary of Significant Accounting Policies (Details) $ in Thousands		12 Months Ended
	Apr. 24, 2014	Dec. 31, 2016 USD ($) shares	Nov. 17, 2016 USD ($)	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 shares	Dec. 31, 2013 shares
Basis Of Presentation [Line Items]
Cash and cash equivalents		$ 130,000		$ 117,300
Interest earning deposits with banks		5,600		2,200
Federal funds sold		56,100		65,900
Loans, net of deferred fees and costs		23,604,633		22,177,069
Federal Reserve Bank stock held		98,600	$ 97,300	1,200
Federal Home Loan Bank stock held		$ 71,300		$ 67,100
Stock split, conversion ratio	0.1429
Options outstanding (in shares) | shares		973,361		1,741,975	2,550,046	3,220,110
Non-interest income revenue streams in scope		50.00%
Non-employee Director [Member]
Basis Of Presentation [Line Items]
Vesting period		3 years
Non-employee [Member]
Basis Of Presentation [Line Items]
Vesting period		3 years
Low Income Housing Tax Credit Partnerships [Member]
Basis Of Presentation [Line Items]
Carrying value of VIE assets and liabilities, net		$ 26,500		$ 18,900
DRR Methodology [Member]
Basis Of Presentation [Line Items]
Loans, net of deferred fees and costs		$ 7,600,000
Loans, net, percent		31.80%
Maximum [Member]
Basis Of Presentation [Line Items]
Retail loans and commercial loans, evaluated for impairment		$ 1,000
Useful life		10 years
Minimum [Member]
Basis Of Presentation [Line Items]
Useful life		8 years
Cash And Cash Equivalents [Member]
Basis Of Presentation [Line Items]
Total deposits		$ 533		$ 100